# Thermodynamics Questions and Answers – Specific Heat at Constant Volume and Pressure and Control Volume

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This set of Thermodynamics Questions and Answers for freshers focuses on “Specific Heat at Constant Volume and Pressure and Control Volume”.

1. The specific heat of a substance at constant volume is defined as the rate of change of ___ with respect to ___
a) specific internal energy, temperature
b) work, pressure
c) specific internal energy, pressure
d) heat, temperature

Explanation: cv=∂u/∂T at constant volume.

2. Heat transferred at constant _____ increases the _____ of a system.
a) pressure, increases
b) volume, increases
c) both of the mentioned
d) none of the mentioned

Explanation: At constant pressure, (dQ)=dh and at constant volume, Q=Δu.

3. Specific heat of a substance at constant volume is a property of the system.
a) true
b) false

Explanation: Since T,v and u are the properties of the system, specific heat at a constant volume is a property of the system.

4. The specific heat of a substance at constant pressure is defined as the rate of change of ___ with respect to ___
a) work, pressure
b) enthalpy, temperature
c) enthalpy, pressure
d) heat, temperature

Explanation: cp=∂h/∂T at constant pressure.

5. The heat capacity at constant pressure Cp
a) m/cp
b) cp/m
c) mcp
d) none of the mentioned

Explanation: Cp=(mass*specific heat at constant pressure).

6. Specific heat of a substance at constant pressure is a property of the system.
a) true
b) false

Explanation: cp is a property of a substance just like cv.

7. When there is mass transfer across the system boundary, the system is called
a) isolated system
b) closed system
c) open system
d) none of the mentioned

Explanation: Basic definition of an open system.

8. If a certain mass of steam is considered as the thermodynamic system, then the energy equation becomes
a) Q=ΔKE + ΔPE – ΔU + W
b) Q=ΔKE + ΔPE – ΔU – W
c) Q=-ΔKE – ΔPE + ΔU + W
d) Q=ΔKE + ΔPE + ΔU + W

Explanation: Q=ΔE + W and E=KE + PE + U.

9. The surface of the control volume is known as the control surface.
a) true
b) false

Explanation: This is same as the system boundary of the open system.

10. Steady flow means that the rates of flow of mass and energy across the control surface
a) varies
b) remains constant
c) depends on the control surface
d) none of the mentioned 